Have you thought about this long
Well, actually the answer is quite simple. Since the building was constructed prior to civil rights legislation and official desegregation, the extra bathrooms were intended to provide accommodations to both races.
By the early 1940s, the War Department (later turned into the Department of Defense) had spread itself all around Washington, D.C., dispersing its workforce among many disjoint buildings. Eventually a plan for the War Department's new home was drawn up and approved by President Roosevelt. Construction costs were estimated to be around $35 million.
Congress, on the other hand, was not very enthusiastic about the plan. They argued that the Pentagon would be an eyesore because of its massive dimensions. Some expressed doubts about it ever filling up to its full capacity, noting that after World War II was over there wouldn't be a need for such a large staff.
In any case the plan was approved and construction set in motion. The architect was George E. Bergstrom and the prime contractor was the John T. McShain Company of Philadelphia. The immense project was completed on January 15, 1943. Final price tag: ~$80 million.
The 5-story Pentagon building has 5 concentric rings connected by 10 spoke-like corridors ranging out from the inner, or A, ring. The combined length of the corridors and rings is 17 1/2 miles and the total gross floor area is more that 6.5 million square feet. The length of each of
the five outer walls is 921 feet and the structure is slightly over 71 feet in height.
Because of the unique design of the building, it takes no more than 10 minutes to walk between any two extremities. The Pentagon includes numerous snack bars, cafeterias, dining rooms, a shopping concourse, banks, a metro station, a bus platform, and many other facilities including (important!) an overabundance of bathrooms. Its population has varied over the years, peaking during wartime periods at well over 30,000.
The Pentagon was one of the targets of the September 11, 2001 terrorist attacks on the United States of America.